The present invention relates to thermal inkjet printers characterized by a high volumetric efficiency in a compact print cartridge.
In any office product the overall size of the product has an effect on the cost and sell appeal of the product. In the inkjet printer market, the foot print of a personal printer is a key selling point if the printer can be made small enough to fit on a customer's desk top. In previous inkjet printers the printhead has been made with a small footprint. However, it is a goal of the present invention to permit a four cartridge color printer to have a footprint similar to such prior single pen printers.
When an inkjet product prints onto a page, the carriage must travel across the page such that every nozzle of every pen has an opportunity to reach the full paper area. In inkjet devices, the paper is generally driven along one axis of motion and the printhead is driven along a carriage scan axis which is perpendicular to the media advance axis. This invention addresses shortening the travel along the media scan axis, as well as reducing the overall size of a printhead cartridge that is supplied from an off-board ink reservoir.
For a single printhead product, the pen axis must travel the width of the paper plus the width of the printhead. For a four cartridge product, the carriage must travel the width of the paper, plus the width of the four-printheads plus the space between the printheads required to mount them. The paper width is fixed (unless it is driven relative to the pens by a third axis of motion).
As the product width is reduced, the volume of material required for fabrication and the size of plastic parts go down, reducing the molding machine size and thus the molding cost. The carriage is supported by beams and/or slide rods that must span the length of travel. As the length of travel increase, the stiffness requirements of those beams and rods cause their cross-sections, and thus their cost, to also increase. Thus any decrease in the spanned length is a cost benefit.
It is therefore an object of this invention to provide a cartridge for a inkjet having a substantially reduced dimension in the direction the pen is scanned during operation across the surface of the print medium.
A further object is to provide a inkjet printer of relatively small width, including a reduced width carriage one or more printheads of reduced width.